The present invention relates to data storage devices. More specifically, the present invention relates to data reconstruction for a data storage device, such as a disc drive, tape drive, or optical drive.
Two conventional computer models have become well known in the industry of computing. The first is a mainframe computing model and the second is a clustered computing model.
The traditional progression for an end user in the mainframe computing model is to purchase an initial system, and when additional processing capabilities are required, to replace the initial system with a bigger system. At various points in this cycle, traumatic discontinuities occur. For example, if the user outgrows the architecture of the initial system, the user may need to convert from one operating system to another, or even from one vendor""s proprietary architecture to that of another vendor, when the second upgraded mainframe system is purchased. These changes entail enormous costs for the organization purchasing the upgrade, in both dollars and employee time. Therefore, such conversions are avoided, in many cases.
In addition, the mainframe model entails poor residual value of computer equipment. Thus, the system replacement often results in invested capital which is substantially completely lost when the initial system is replaced by an upgraded system. Further, larger upgraded systems tend to be sold in lower volumes than smaller systems. Thus, each new system upgrade typically has a higher cost of computing than the previous system.
In a clustered computing model, a mainframe computer is replaced with a cluster of smaller, standards-based servers. This can offer many advantages over the mainframe model. Since the cluster may start off as only a single system, the threshold to entering the cluster model is lower. Further, such smaller systems are typically sold in high volume, making the cost of computing less. Also, such systems are standards based in that they do not exhibit dependence on proprietary architectures. This provides for the availability of equipment from multiple sources which allows the user to choose the best alternative with each subsequent purchase.
Still other advantages present themselves with the clustered computing model. Upgrade costs can be controlled more precisely by adding only the amount of additional resources required to meet existing and immediate future needs. Further, the user can choose from a wide variety of vendors, without concern about migration or conversion to a new architecture. Similarly, with the right architecture, there may never be a need for conversion to another operating system.
Still, the clustered computing model does have disadvantages and problems. For example, the clustered computing model encounters difficulty in providing clustered systems with the ability to share data in a way that allows the cluster to take on the workload that a single mainframe could perform. For example, it is currently very difficult to implement clustered models where each of the servers in the cluster are required to process transactions on the same data. Examples of some such applications include an airlines reservations system or a financial institution""s complete inventory of transactions.
The second disadvantage of the clustered computing model simply involves the lack of extensive experience in managing storage and data which exists in the mainframe environment. Such experience has evolved into management software that is simply not yet available in the standards based cluster environment.
Conventional disc drives also include disadvantages which are related to the loss of operating system information. For example, a conventional disc drive contains millions of sectors of data. For any number of different reasons, one or more of the sectors may become unreadable or corrupted. If the sector which becomes unreadable is one that is used for a special purpose by the operating system, the entire disc space in the disc drive may be rendered unusable, even if the entire rest of the disc drive can be read. For example, in a personal computer environment, the master boot record, partition boot record, file attribute table (FAT) or the root directory can be become unreadable or corrupt. This can cause the loss of essentially the entire contents of the disc drive. No conventional operating system has the ability to recover all the readable data in the face of losing such key file system management data. This represents a tremendous loss for a user, and is especially unfortunate since the data that is lost is operating system related, and has little or nothing to do with the actual data stored on the disc drive, which cannot be read.
To date, any service for recovering data in such instances is typically very cumbersome. Such services generally require physically removing the disc drive from its operating environment and sending it to a company or service provider engaged in the service of recovering such data. This service is provided with no guarantee of success, and with no protection against the consequent breach of privacy which attends the relinquishing of the disc drive for this purpose.
The present invention addresses these and other problems, and offers other advantages over the prior art.
The present invention is drawn to a hybrid data reconstruction system and method for a data storage device. Data is selectively stored according to one of two or more redundancy schemes such that critical data is stored according to a scheme which has a higher degree of redundancy.